I2O Practical Zoology. 



2. Behind the cerebrum is the undivided cerebellum. 



3. Running backward from the under side of the cerebellum is 

 the spinal cord ; trace it back into the backbone. Make drawings 

 of the brain, as seen from above and as seen from the side. 



THE SKELETON OF THE PIGEON. 



Notice the lightness of the whole skeleton. What part of the 

 pigeon's weight is bone? Compare the eye cavity with that of 

 man. The lower jaw does not join the skull directly, as in 

 man, but is joined to an irregular bone, which, in turn, joins the 

 skull. This is the quadrate bone. The hole by which the spinal 

 cord leaves the brain cavity is the occipital foramen ; in front of 

 this foramen is a little, rounded projection, the occipital condyte. 

 Observe how this condyle fits into a cavity in the first vertebra of 

 the neck. Count the vertebrae of the neck, or cervical vertebrae. 

 Observe the consolidation of the vertebras in the back ; note 

 the joint in each rib, and the arrangement for bracing the ribs 

 together. Press the breastbone alternately toward the back 

 and away from it, meanwhile watching the joints in the ribs. 



The " wishbone " corresponds to the two " collar bones " of 

 man. Alongside the two branches of the wishbone are the cora- 

 coid bones ; what especial need of such bones in this place ? In 

 the wing find, in the arm, the humerus ; in the forearm, the ulna 

 and radius. The hand has only part of the fingers developed ; a 

 little bone, representing the thumb, is present (which bore the 

 feathers of the " false wing "). In the thigh is the femur ; in the 

 leg is the tibia ; and alongside it, the small fibula. The bone 

 above the foot represents the consolidated bones of the human 

 ankle and foot as far as the toes. What evidence is there of such 

 consolidation ? 



THE HEN'S EGG. 



So place a hen's egg in a basin of water that it cannot roll, 

 mark the upper side plainly, and boil it hard ; keep track of the 

 side that was uppermost. 



